From Elemental Sulfur to Hydrogen Sulfide in Agricultural Soils and Plants

Abstract

Sulfur is an essential element in determining the productivity and quality of agricultural products. It is also an element associated with tolerance to biotic and abiotic stress in plants. In agricultural practice, sulfur has broad use in the form of sulfate fertilizers and, to a lesser extent, as sulfite biostimulants. When used in the form of bulk elemental sulfur, or micro- or nano-sulfur, applied both to the soil and to the canopy, the element undergoes a series of changes in its oxidation state, produced by various intermediaries that apparently act as biostimulants and promoters of stress tolerance. The final result is sulfate S+6, which is the source of sulfur that all soil organisms assimilate and that plants absorb by their root cells. The changes in the oxidation states of sulfur S0 to S+6 depend on the action of specific groups of edaphic bacteria. In plant cells, S+6 sulfate is reduced to S−2 and incorporated into biological molecules. S−2 is also absorbed by stomata from H2S, COS, and other atmospheric sources. S−2 is the precursor of inorganic polysulfides, organic polysulfanes, and H2S, the action of which has been described in cell signaling and biostimulation in plants. S−2 is also the basis of essential biological molecules in signaling, metabolism, and stress tolerance, such as reactive sulfur species (RSS), SAM, glutathione, and phytochelatins. The present review describes the dynamics of sulfur in soil and plants, considering elemental sulfur as the starting point, and, as a final point, the sulfur accumulated as S−2 in biological structures. The factors that modify the behavior of the different components of the sulfur cycle in the soil–plant–atmosphere system, and how these influences the productivity, quality, and stress tolerance of crops, are described. The internal and external factors that influence the cellular production of S−2 and polysulfides vs. other S species are also described. The impact of elemental sulfur is compared with that of sulfates, in the context of proper soil management. The conclusion is that the use of elemental sulfur is recommended over that of sulfates, since it is beneficial for the soil microbiome, for productivity and nutritional quality of crops, and also allows the increased tolerance of plants to environmental stresses.

Hydrogen sulfide (H2S) signaling in plant development and stress responses

“…1 ). In agriculture, sulfur is widely applied in the form of sulfate fertilizers (Fuentes-Lara et al 2019 ), and transported by a proton/sulfate co-transport mode mediated by sulfate transporters (SULTRs) in root epidermal cells (Buchner et al 2004 ). Subsequently, the sulfate is loaded into the xylem vessels and distributed into the entire plant (Leustek et al 2000 ), which is stored into vacuoles via SULTR4:1 (Takahashi et al 2011 ) or transported to chloroplasts via SULTR3:1 to launch the assimilatory activities (Gotor et al 2015 ).…”

Temporal trends of sulfur levels in soils of northwestOhio(USA) between 2002 and 2014

“…Sulphur inputs by weathering of parent material is difficult to distinguish from other sources, such as mineralization, and do not provide more than 1 kg of S ha −1 yr −1 , mainly because of its constant and slow release process (Haneklaus, Bloem, & Schnug, 2000). Reduced sulfur compounds as sulfides (S 2− ), elemental sulfur (S 0 ), and sulfites (SO 3 2− ) are found, in small amounts, mostly in strongly acid and/or in reduced soils (Fuentes-Lara et al, 2019). Other sulfur minerals, as Ca and Mg sulfates, are significant for incipient soils and/or drier regions of the world, since in long-term agricultural soils or humid areas these minerals are leached by rainfall and rarely found (Dick et al, 2008).…”

Impacts ofDesulfobacteralesandChromatialeson sulfate reduction in the subtropical mangrove ecosystem as revealed by SMDB analysis

“…S9). Prokaryotes, algae, plants, and fungi undergo sulfate assimilatory reduction to produce various organic compounds, such as amino acids (Fuentes-Lara et al, 2019). Several nutrients, such TOC, TN, and TP (p < 0.05, Supplementary Table S6), are vital for rhizosphere microorganisms to gain energy.…”